1. Field of the Invention
The present invention relates to a shut-off valve for use in a compression sack.
2. Description of Background Art
Compression sacks provided with a shut-off valve for compactly packing clothing or bedding therein have long been known in the art.
Typically, to pack clothing in such a compression sack, a zipper disposed on an access port for contents is closed, and the compression sack is manually compressed, or a vacuum connected by a nozzle to the shut-off valve is actuated to draw out air inside the sack and to expel same through the shut-off valve. Since the shut-off valve may function to limit airflow to a single or outward direction, air may be prevented from reentering the compression sack. As a result, extremely low air pressure can be maintained.
The volume of such stored goods as clothing or bedding contained in the compression sack can be decreased by removing air within the sack. As a result of this decreased volume, more compact packaging can be achieved.
Shut-off valves may take various shapes. For example, the shut-off valve may have a flat, cylindrical body made of a flexible synthetic resin film provided with an opening. The cylindrical body may include a bent passage formed, e.g., by hot-pressing part of the film.
When such a shut-off valve is mounted on the compression sack designed for maintaining a low internal air pressure, the compression sack is in such a state that air can be easily introduced into the sack via the shut-off valve during deaeration. However, since the passage remains crushed flat, it does not allow the entry of air to flow from outside into the sack. Thus, the air pressure within the compression sack remains low.
However, even though such a shut-off valve has a simple structure, the passage itself may not remain closed, and the introduction of some air from the outside may not be avoided completely. Thus, air may gradually reenter the sack with the lapse of time.
Therefore, the goal of the present invention is to provide a shut-off valve having a simple structure and a function which serves to prevent the entry of air in an effective manner. The shut-off valve of the present invention is not only capable of removing air from the sack, but is also capable of charging the sack with air or allowing air to reenter the sack when desired.
To achieve this goal, a first aspect of the present invention provides a shut-off valve in which an air passage 41 having a flat and substantially cylindrical shape in cross section is formed by closing both sides of opposed cladding sheets 43a, 43b by means of closing members 43e, 43f. The air passage 41 has openings 43c, 43g at the both ends, and a valve body sheet 42 inside thereof. The valve body sheet 42 includes a fixed member 42a secured to said cladding sheet 43b, a first flap member 42b, and a second flap member 42c, with the fixed member 42a disposed in a central position therebetween. Both of the flap members are movable about the fixed member 42a. The first flap member 42b serves to prevent air from flowing from opening 43c at one end to opening 43g at the other end of said air passage 41 by maintaining close contact between the first flap member 42b and a surface 43i of the other cladding sheet 43a at the air passage side 41. Similarly, the second flap member 42c serves to prevent air from flowing in the reverse direction from opening 43g to opening 43c of the air passage 41 by maintaining close contact between the second flap member 42c and the surface 43i of the other cladding sheet 43a at the air passage side 41.
Thus, a shut-off valve is provided which alternatively can perform the function of removing air from the sack at one time and, at a later time, charging the sack with air again.
In a second aspect of the present invention, the shut-off valve as described above has opposed cladding sheets 43a, 43b, the cladding sheet 43a also serving as a sheet 11 from which a sealable sack may be made.
This makes it possible to produce a shut-off valve formed integrally with a sack, thereby avoiding use of redundant materials and reducing production costs.
In a third aspect of the present invention, a shut-off valve is provided wherein the air passage 41 having a flat and substantially cylindrical shape in cross section is formed with an opening, either 43c, 43g, disposed at each end in one axial direction and along at least one of the opposed cladding sheets 43a, 43b. The closing members 43e, 43f cross at right angles to said one axial direction and are disposed at both ends in the other axial direction and along at least one of said cladding sheets. A valve body sheet 42 is secured to a surface 43h of one cladding sheet 43b at the air passage side, which surface is located midway in the air passage 41 and extends along the cladding sheet 43b from one closing member 43e to the other closing member 43f. The closing member 43f is the origin of first and second check valves. The first check valve serves to prevent air from flowing from opening 43c at one end to opening 43g at the other end of the air passage 41 by maintaining close contact between a part of the valve body sheet 42 and the surface 43i of the cladding sheet 43a at the air passage side 41. Similarly, the second check valve serves to prevent air from flowing in the reverse direction from opening 43g to opening 43c. A rod 5 can be inserted into the air passage 41 in such a manner that openings 43c, 43g at either end of the air passage 41 may communicate with each other by virtue of the rod 5. As a result, contact between a part of the valve body sheet 42 and the surface 43i of the cladding sheet 43a at the air passage side 41 will be severed, allowing air to run through the air passage. The air passage 41 is closed again by pulling out the rod 5.
Thus, a shut-off valve is provided which performs the dual function of removing air from the sack and filling the sack with air. In other words, the operating mode can be switched from one mode of allowing the passage of air, to the other mode of preventing the introduction of air.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.